invalid bit in WRB indicates to FW that IO was invalidated before WRB
was fetched from host memory.

For SkyHawk, this invalid bit in WRB is at a different offset.
Use amap_iscsi_wrb_v2 to mark invalid bit for SkyHawk.
Signed-off-by: Jitendra Bhivare <jitendra.bhivare@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>